The present invention relates to railway car overheated bearing detection systems and in particular to a system for determining if a railway car under observation is a "freight" car.
A major cause of train derailment is the overheating of the wheel bearings, commonly known as "hot boxes". Railroads often utilize infra-red scanner systems along their tracks to scan the bearings of passing trains and to generate an alarm in the event an overheated bearing is detected. Such a system may, for example, comprise the Hot Box Detective System marketed by the Servo Corporation of America of Hicksville, New York.
A problem with such infra-red systems arises from the fact that not all railway car axles have the same type of bearings and certain bearings inherently run hotter than other bearings. Specifically, roller bearings run at temperatures sufficiently high to be considered an overheated friction bearing. As a result, it has been necessary to provide discriminator circuits to determine whether a particular bearing under observation is a friction bearing or a roller bearing. Such discriminators may, for example, comprise the Universal Alarm System of the aforementioned Servo Corporation.
While the primary objective of hot box detector systems is to detect every hot box of passing trains, a secondary objective is to eliminate as many false alarms as possible. The unnecessary stopping of a railroad train is a very expensive and time wasting nuisance. A false alarm will be generated each time the discriminator circuit fails to recognize that a passing bearing is a normally operating roller bearing and instead treats it as an overheated friction bearing.
In North America, friction bearings are only used on freight cars while roller bearings may be used on freight cars as well as passenger cars and locomotives. Accordingly, if the determination can be made that the railway car passing an infrared sensor scanning station is not a freight car, then the discriminator circuit need not make the determination as to whether a passing bearing is a roller bearing or friction bearing since it is known that the bearings can only be roller bearings. On the other hand if the determination is made that a passing car is a freight car, then the further determination must be made as to whether roller bearings or friction bearings are under observation.
In view of the above, it is the principal object of the present invention to provide a system for the determination of whether a railway car passing a hot box scanning station is a freight car.
A further object is to provide such a system which may be implemented with conventional components and which is compatible with existing hot box detector systems and equipment.